Prey individuals vary in their body size even within groups and are often scattered heterogeneously in patchy environments. A foraging predator has to evaluate and select the patches where it can maximize its energetic gains. We studied the foraging behavior of a predator (little egret, Egretta garzetta) hunting prey groups (goldfish, Carassius auratus) that differed in body size and composition across three different patches (one large, one mixed, and one small). We quantified predator’s stay time, return time and size-specific kills of the prey. The egret spent a similar amount of total time foraging in the three patches; however, it spent more time per-visit in pools containing large-bodied fish and also returned to those pools soonest after leaving to forage elsewhere, suggesting that the predators employ a time management strategy to maximize energetic returns. Furthermore, the egret preferentially killed larger individuals. Such size-selective predation can shift the prey size structure in the landscape and influence the dynamics of species interactions and eventually the structure of the communities.

即使在群体内，猎物个体的体型也各不相同，并且通常分散在零散的环境中。觅食的捕食者必须评估和选择可以最大化其能量收益的斑块。我们研究了捕食者（小白鹭，Egretta garzetta）狩猎猎物群体（金鱼，鲫鱼）的觅食行为) 在三个不同的斑块（一个大的、一个混合的和一个小的）上的体型和组成不同。我们量化了捕食者的停留时间、返回时间和特定大小的猎物杀死。白鹭在三个斑块中觅食的总时间相似。然而，它每次访问都花更多的时间在含有大型鱼类的水池中，并且在离开到其他地方觅食后最快地返回这些水池，这表明捕食者采用时间管理策略来最大化能量回报。此外，白鹭优先杀死较大的个体。这种大小选择性捕食可以改变景观中的猎物大小结构，并影响物种相互作用的动态，最终影响群落的结构。